Laundry treating apparatus

ABSTRACT

A laundry treating apparatus is provided. The laundry treating apparatus includes a cabinet, a drum accommodated in the cabinet, and a dynamic absorber provided to absorb oscillation of the cabinet. The dynamic absorber includes a first moving mass movably provided on the support plate to absorb oscillation transmitted to the cabinet and a second moving mass movably provided on the support plate to absorb oscillation transmitted to the cabinet. Each of the first and second moving masses includes a single mass made of a metal material or a mass in which a plurality of thin metal plates are coupled to overlap each other, and the first moving mass has a mass greater than that of the second moving mass.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority under 35 U.S.C. 119 and 35U.S.C. 365 to Korean Patent Application Nos. 10-2016-0086343 (filed onJul. 7, 2016), 10-2016-0140290 (filed on Oct. 26, 2016), and10-2017-0069026 (filed Jun. 2, 2017), which are hereby incorporated byreference in their entireties.

BACKGROUND 1. Field

The present disclosure relates to a laundry treating apparatus.

2. Background

In the case of home appliance provided with a rotating drum such as awashing machine or a dryer, as the rotational speed (rpm) of the drumincreases, horizontal excitation force is generated by eccentricity oflaundry put into the drum, i.e., a load. Particularly, in thedehydration process, transient oscillation (damped oscillation(vibration)) in which horizontal oscillation displacement of a cabinetof the washing machine rapidly increases at a resonant frequency pointof the cabinet of the washing machine occurs while the rotational speedof the drum increases. Also, when the drum is constantly maintained atthe maximum speed, continuous oscillation (steady-state oscillation(vibration)) in which the same oscillation is constantly repeatedoccurs.

The transient oscillation causes a phenomenon in which the washingmachine is wobbled in a lateral direction while the rotational speed ofthe drum increases. Also, the transient oscillation is more pronouncedin a stack type washing machine in which the washing machine is spacedapart from the ground. For example, in the case of a compact washingmachine or the stack type washing machine that is stacked on a topsurface of an object for storing laundry, the oscillation displacementof the transient oscillation is larger than that of a general washingmachine that is placed directly on an installation surface, and thetransient oscillation occurs at a low speed operation. That is, a timepoint at which the transient oscillation occurs is accelerated in thestack type washing machine when compared to a washing machine that isplaced directly on the floor.

To absorb the transient oscillation, a dynamic absorber is generallyinstalled in the washing machine. The dynamic absorber may be a dynamicabsorber using a principle of absorbing the oscillation of the washingmachine by oscillating in a horizontal direction in a phase opposite tothat of the horizontal excitation force generated by the rotation of thedrum by about 180 degrees.

In detail, when the rotation of the drum is accelerated, the horizontalexcitation force is generated by rotation of the eccentric load(laundry) as described above. Also, when the number of revolutions ofthe drum increases to reach the resonant frequency of the drum, thecabinet of the washing machine harmonically oscillates at a resonantpoint in a phase difference of about 90 degrees with respect to theexcitation force.

Also, the dynamic absorber harmonically oscillates at the resonant pointin a phase difference of about 90 degrees with respect to theoscillation of the cabinet of the washing machine. As a result, theexcitation force and the dynamic absorber oscillate in a phasedifference of about 180 degrees therebetween in opposite directions tooffset the oscillation, thereby the cabinet of the washing machine frommoving.

A technique in which the dynamic absorber is provided in a washingmachine is disclosed in U.S. Pat. No. 8,443,636. The disclosed dynamicabsorber has a structure in which a frame is provided on a bottomsurface of a casing of a washing machine, a viscoelastic member isprovided on a top surface of the frame, and a moving mass for absorbingoscillation is provided on a top surface of the viscoelastic member.

The disclosed dynamic absorber has limitations as follows. First, sincethe viscoelastic member is provided on a bottom surface of the movingmass, a load of the moving mass may continuously act on the viscoelasticmember to cause damage and performance deterioration of the viscoelasticmember. Second, when the moving mass oscillates horizontally, since theviscoelastic member absorbs the oscillation by using shear stress actingin the lateral direction, there is a limitation that transientoscillation is not effectively absorbed due to a low damping ratio.Although the feature in which the oscillation is effectively absorbed inthe entire range of the number of revolutions of the drum is disclosed,the disclosed dynamic absorber may have an effect of absorbingcontinuous oscillation, but the capability to absorb transientoscillation with suddenly increasing oscillation displacement may besignificantly reduced.

Third, since the share stress alternately acts on the viscoelasticmember, there is a disadvantage that possibility of damage of theviscoelastic member increases, and the lifespan of the viscoelasticmember is shortened. Fourth, when the horizontal oscillation is appliedto the washing machine, and thus, the moving mass moves horizontally ina direction opposite to the oscillation, and viscoelastic member is bentwhile an upper end of the viscoelastic member moves in the lateraldirection. As a result, there is a limitation that the moving mass isnot shaken in the lateral direction while maintaining the horizontalstate so as to absorb the oscillation. That is to say, when the movingmass is shaken in the lateral direction to absorb transverseoscillation, left and right ends of the moving mass are tilted downwarddue to the bending of the viscoelastic member. As a result, thehorizontal oscillation acting on the washing machine may not beeffectively absorbed.

The above reference is incorporated by reference herein whereappropriate for appropriate teachings of additional or alternativedetails, features and/or technical background.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 is a perspective view of a laundry treating apparatus accordingto an embodiment;

FIG. 2 is an exploded perspective view of the laundry treating apparatusincluding a dynamic absorber according to an embodiment;

FIG. 3 is a perspective view of the dynamic absorber according to anembodiment;

FIG. 4 is an exploded perspective view of the dynamic absorber;

FIG. 5 is a perspective view of a support plate constituting the dynamicabsorber according to an embodiment;

FIG. 6 is a plan view of the support plate;

FIG. 7 is a longitudinal cross-sectional view taken along line 7-7 ofFIG. 6;

FIG. 8 is a plan view of a first moving mass according to an embodiment;

FIG. 9 is a perspective view of the first moving mass;

FIG. 10 is a view illustrating a buffer structure for verticaloscillation of the first moving mass according to an embodiment;

FIG. 11 is a longitudinal cross-sectional view taken along line 11-11 ofFIG. 10;

FIG. 12 is a cross-sectional view of a separation prevention structurefor preventing the moving mass from being separated from the supportplate while the laundry treating apparatus is carried;

FIG. 13 is a perspective view of a second moving mass according to anembodiment;

FIG. 14 is a top perspective view of a support according to anembodiment;

FIG. 15 is a bottom perspective view of the support;

FIG. 16 is an exploded perspective view of the support;

FIG. 17 is a longitudinal cross-sectional view taken along line 17-17 ofFIG. 14;

FIG. 18 is a top perspective view of an upper slider constituting aslider according to an embodiment;

FIG. 19 is a bottom perspective of the upper slider;

FIG. 20 is a top perspective view of a lower slider constituting theslider;

FIG. 21 is a bottom perspective view of the lower slider;

FIG. 22 is a longitudinal cross-sectional view taken along line 22-22 ofFIG. 3;

FIG. 23 is a top perspective view of a second elastic damper accordingto an embodiment;

FIG. 24 is a bottom perspective view of the second elastic damper;

FIG. 25 is a top perspective view of a first elastic damper according toan embodiment;

FIG. 26 is a bottom perspective view of the first elastic damper;

FIG. 27 is a longitudinal cross-sectional view taken along line 27-27 ofFIG. 25;

FIG. 28 is a graph illustrating oscillation displacement of a laundrytreating apparatus on which a dynamic absorber including only a movingmass for absorbing transient oscillation is mounted; and

FIG. 29 is a graph illustrating oscillation displacement of the laundrytreating apparatus on which the dynamic absorber is mounted according toan embodiment.

DETAILED DESCRIPTION

Hereinafter, a laundry treating apparatus according to an embodimentwill be described in detail with reference to the accompanying drawings.

First, the terms described in this specification will be defined. Thetransient (damped) oscillation (vibration), which will be describedbelow, is defined as oscillation in which, when a drum into whichlaundry is put rotates to be accelerated for rinse or dehydration,oscillation displacement of a cabinet rapidly increases at a resonantpoint of the drum. Also, continuous (steady-state) oscillation(vibration), which will be described below, is defined as oscillationthat is continuously generated with almost constant oscillationdisplacement while the drum is maintained at the maximum speed. Also,the improvement or the absorption of the transient oscillation or thecontinuous oscillation by the dynamic absorber according to anembodiment may be understood as a phenomenon in which the dynamicabsorber removes or minimizes the transient oscillation or thecontinuous oscillation to minimize the oscillation of the cabinet.

FIG. 1 is a perspective view of a laundry treating apparatus accordingto an embodiment, and FIG. 2 is an exploded perspective view of thelaundry treating apparatus including a dynamic absorber according to anembodiment. Referring to FIGS. 1 and 2, a laundry treating apparatus 10according to an embodiment may include a cabinet 11, a dynamic absorber(also referred to as a dynamic dampener or vibration dampener) 20provided on a top surface of the cabinet 11 to absorb oscillationtransmitted to the cabinet 11, a drum (not shown) accommodated in thecabinet 11, and a tub 16 accommodating the drum.

In detail, the cabinet 11 includes a front cabinet 111, side cabinets112, and a rear cabinet 113. A top plate 12 is placed on a top surfaceof the cabinet 11 to cover an upper opening of the cabinet 11. Also, adoor 15 is rotatably coupled to the front cabinet 111 so that laundry isput into the drum. Also, a detergent box 14 and a control panel 13 maybe provided on an upper end of the front cabinet 111.

Also, the laundry treating apparatus 10 may be provided directly on aninstallation surface or provided on a separate stacking body W having apredetermined height h. The separate stacking body W may be anindependent washing machine having a small volume or a storage box forstoring objects including the laundry, but is not limited thereto.

The dynamic absorber according to an embodiment is seated on the topsurface of the cabinet 11 and covered by the top plate 12 so that thedynamic absorber 20 is not exposed to the outside. Also, left and rightends of the dynamic absorber 20 are seated on upper ends of the left andright side cabinets 112, respectively. Also, since the detergent box 14and the control panel 13 are provided in an inner upper portion of thecabinet 11, the dynamic absorber 20 may be provided to be spacedbackward from a front end of the cabinet 11 so that the dynamic absorber20 does not interfere with the detergent box 14 and the control panel13.

For example, a horizontal distance between a front end of a supportplate (or support) 21 (see FIGS. 3 and 4) and the front cabinet 111 maybe set to be greater than that between a rear end of the support plate21 and the rear cabinet 113. However, an embodiment of the presentdisclosure is not limited thereto. For example, the dynamic absorber 20may be provided at a center of the top surface of the cabinet 11.

Hereinafter, a structure and function of the dynamic absorber 20 will bedescribed in detail with reference to the accompanying drawings. FIG. 3is a perspective view of the dynamic absorber according to anembodiment, and FIG. 4 is an exploded perspective view of the dynamicabsorber. Referring to FIGS. 3 and 4, the dynamic absorber 20 accordingto an embodiment may include a support plate 21, a moving mass (alsoreferred to as a mass or mass body) 22 slidably provided on the supportplate, an elastic damper 25 provided on a side surface of the movingmass 22, and a sliding guide member supporting a bottom surface of themoving mass 22.

In detail, the moving mass 22 is slidably provided on the support plate21 in a horizontal direction, i.e., a lateral direction of the laundrytreating apparatus 10. Also, the moving mass 22 may include a firstmoving mass (or first mass body) 23 and a second moving mass (or secondmass body) 24 provided at a rear side of the first moving mass 23. Here,it is noted that the front moving mass may be defined as the secondmoving mass, and the rear moving mass may be defined as the first movingmass.

Also, one of the first and second moving masses 23 and 24 may be adamper for absorbing the transient oscillation of the cabinet 11, andthe other may be a damper for absorbing the continuous oscillation ofthe cabinet 11. Also, the damper for absorbing the transient oscillationmay be provided at the front or the rear of the damper for absorbing thecontinuous oscillation. In this embodiment, the first front moving mass23 may be the damper for reducing the continuous oscillation, and thesecond rear moving mass 24 may be the damper for reducing the transientoscillation. Also, the damper for reducing the continuous oscillationmay have a mass greater than that of the damper for reducing thetransient oscillation. This is because the continuous oscillation isgenerated at high-speed rotation, and the transient oscillation isgenerated at low-speed rotation that is relatively less than that of thecontinuous oscillation.

Also, the elastic damper 25 may include a first elastic damper 26supporting both side surfaces of the first moving mass 23 and a secondelastic damper 27 supporting both side surfaces of the second movingmass 24. The elastic damper 25 is made of a material havingpredetermined elasticity and attenuation to absorb an impact generatedwhen the moving mass 22 moves in the lateral direction in a phaseopposite to that of excitation force of the drum. That is, the elasticdamper 25 may prevent the moving mass 22 from directly colliding withthe side surface of the support plate 21 and push the moving mass 22 byusing the elasticity in an opposite direction.

The sliding guide member includes a support (or s support body) 28 and aslider (also referred to as a slider plate or a friction plate) 29. Indetail, the support 28 is provided on the bottom surface of the damperfor reducing the continuous oscillation, and the slider 29 is providedon the bottom surface of the damper for reducing the transientoscillation. Thus, in this embodiment, the support 28 may be providedbelow the first moving mass 23, and the slider 29 may be provided belowthe second moving mass 24. Here, to improve the continuous oscillation,it is advantageous that the attenuation of the moving mass is small, andto improve the transient oscillation, it is advantageous that theattenuation of the moving mass is large. Thus, the attenuation of thesupport 28 may be designed to be minimized, and the attenuation of theslider 29 may be designed to be significantly larger than that of thesupport 28. Thus, the attenuation may be adequately determined inconsideration of the resonant frequency generated in the transientoscillation and the mass of the second moving mass 24. In one embodimentdepicted in FIG. 4, no supports 28 are present under second moving mass24, and no sliders 27 are present under first moving mass 23.

Hereinafter, each of components constituting the dynamic absorber 20will be described in detail with reference to the accompanying drawings.FIG. 5 is a perspective view of the support plate constituting thedynamic absorber according to an embodiment, FIG. 6 is a plan view ofthe support plate, and FIG. 7 is a longitudinal cross-sectional viewtaken along line 7-7 of FIG. 6. Referring to FIGS. 5 to 7, the supportplate 21 constituting the dynamic absorber 20 according to an embodimentmay be a support member supporting the moving mass 22, and the movingmass 22 may be provided to be slidable and movable in the lateraldirection on the support plate 21.

In detail, the support plate 21 may include a plate body 211 provided asa rectangular metal plate, a boundary wall 212 surrounded in anapproximately rectangular shape at an outer edge of the plate body 211,a partition wall 213 extending by a predetermined length from the insideof the boundary wall 212, and a cabinet coupling part (or tab) 215extending from an outer edge of the boundary wall 212 and seated on thetop surfaces of the side cabinets 112.

In more detail, the boundary wall 212 and the partition wall 213 mayprotrude by a predetermined height forward from a top surface of theplate body 211 through a forming process to reinforce rigidity of thesupport plate 21. Also, a moving mass accommodation part 214accommodating the moving mass 22 is provided inside the boundary wall212. Each of the boundary wall 212 and the partition wall 213 mayprotrude by a height of about 1 mm to about 15 mm. However, anembodiment of the present disclosure is not limited thereto. Forexample, it is sufficient if each of the boundary wall 212 and thepartition wall 213 protrude by a height that is greater than a thicknessof at least the moving mass 22.

Also, the partition wall 213 may partition the moving mass accommodationpart 214 into a first front accommodation part 214 a and a second rearaccommodation part 214 b. Each of left and right ends of the partitionwall 213 may extend up to an inner edge of the boundary wall 212. Asillustrated in the drawings, both the ends may be spaced a predetermineddistance from each other from the inner edge of the boundary wall 212.Also, in this embodiment, since the first moving mass 23 has a mass (orweight) greater than that of the second moving mass 24, the partitionwall 213 may be provided closer to a rear end than a front end of theboundary wall 212.

The cabinet coupling part 215 may be provided in plurality at left andright edges of the plate body 211. Also, one or plurality of couplingholes 215 a may be defined in each of the cabinet coupling part 215.Also, a coupling member such as a screw may pass through the couplinghole 215 a and then be inserted into each of the top surfaces of theside cabinets 112. Also, an avoiding groove 215 b may be defined betweenthe cabinet coupling parts 215 adjacent to each other in a front andrear direction. The avoiding groove 215 b may be defined to prevent anobject such as a ground line or a bolt head, which is coupled to the topsurface of the side cabinet 112, from interfering with the support plate21.

Also, a plurality of rigidity reinforcement parts 217 are provided on aportion of the plate body 211, which corresponds to the moving massaccommodation part 214. Each of the plurality of rigidity reinforcementparts 217 may be recessed by a predetermined depth downward from abottom surface of the plate body 211 through a forming process. Also,the plurality of rigidity reinforcement parts 217 may be spaced apredetermined distance from each other in the front and rear direction.

In detail, the plurality of rigidity reinforcement parts 217 may includea plurality of forming parts 217 a (or first rigidity reinforcementparts) provided in an area of the first accommodation part 214 a and aplurality of second forming parts 217 b (or second rigidityreinforcement parts) provided in an area of the second accommodationpart 214 b. Also, left and right edges of the plurality of first formingparts 217 a may be connected to the inner edge of the boundary wall 212,and a front end of the frontmost forming part of the plurality of firstforming parts 217 a may be connected to the inner edge of the boundarywall 212.

Also, each of left and right edges of the plurality of second formingparts 217 b may be spaced a predetermined distance from the inner edgeof the boundary wall 212. Also, a front end of the frontmost formingpart of the plurality of second forming parts 217 b may be connected tothe partition wall 213. Also, a rear end of the frontmost forming partof the plurality of second forming parts 217 b may be connected to theinner edge of the boundary wall 212.

Also, a plurality of avoiding holes 218 a may be defined in theplurality of rigidity reinforcement parts 217. The plurality of avoidingholes 218 a may be holes for preventing interference with a head of thecoupling member protruding from the bottom surface of the moving mass22, e.g., a head of the rivet. Also, since the moving mass 22 moves inthe lateral direction, each of the avoiding holes 218 a may have an ovalor long-hole shape having a long side corresponding to a moving distance(displacement) of the moving mass 22. Also, one or plurality of drainholes may be defined in the plate body 211 corresponding to the movingmass accommodation part 214 to quickly discharge moisture generated inthe dynamic absorber to the outside.

Also, a support mounting part 219 may be provided on one of theplurality of first forming parts 217 a. A formation position of thesupport mounting part 219 may be determined according to the mountedposition of the support 28. In this embodiment, two support mountingparts 219 are provided to be spaced apart from each other in the lateraldirection of the support plate 21.

The support mounting part 219 may include a roller hole 219 a, a pair ofhook holes 219 c respectively defined in front and rear sides of theroller hole 219 a, and a pair of roller shaft support parts 219 bprovided between the roller hole 219 a and the hook holes 219 c. Also, aplurality of slider coupling holes 218 b may be defined in the secondforming part 217 b. The slider coupling holes 218 b may be holes forallowing the slider 29 to be fixed to the support plate 21.

A plurality of coupling slits 216 may be respectively defined in leftand right edges of the moving mass accommodation part 214. In detail,the plurality of coupling slits 216 may be defined at points adjacent tothe inner edge of the boundary wall 212 so that the plurality of elasticdampers 25 are coupled to be fitted into the plurality of coupling slits216. Each of the plurality of coupling slits 216 may have a T shape or Ishape having a long side and a short side extending from an end of thelong side in a direction crossing the long side. Since the coupling slit216 has the T shape or I shape, a coupling arm (that will be describedlater) protruding from the bottom surface of the elastic damper 25 maybe easily inserted. A method for inserting the coupling arm of theelastic damper 215 into the coupling slit will be described below withreference to the accompanying drawing.

Also, since the support plate 21 is fixed to the top surface of the sidecabinet 112, oscillation of the cabinet 11 may be transmitted to thesupport plate 21, and thus, the support plate 21 may oscillate togetherwith the cabinet 11.

Here, the support plate 21 may have a primary mode resonant frequencygreater than a maximum rotating frequency of the drum to avoid aself-resonance of the support plate 21 within a rotation section of thedrum. For example, the support plate 21 may have a primary mode naturalfrequency (or a primary mode resonant frequency) of about 20 Hz to about30 Hz.

FIG. 8 is a plan view of the first moving mass according to anembodiment, FIG. 9 is a perspective view of the first moving mass.Referring to FIGS. 8 and 9, the first moving mass 23, which absorbs thecontinuous oscillation, of the moving mass 22 according to an embodimentmay have a rectangular shape having rounded corners. In detail, thefirst moving mass 23 may be made of a metal material having high densityto secure a sufficient mass in a limited space of the inside of thecabinet 11. Also, the first moving mass 23 may be a single massmanufacture through casting or be manufactured by laminating a pluralityof thin metal plates.

When the first moving mass 23 is manufactured by laminating theplurality of thin metal plates, the plurality of thin metal plates maybe coupled by a rivet part 231 to form a single body. Also, although thefour corners of the moving mass 22 are rounded, an embodiment of thepresent disclosure is not limited thereto. Also, the number of rivetparts 231 may be adequately set according to the number and size of thethin metal plates to be laminated so that the plurality of thin metalplates functions like the single mass without being shaken orfrictionized with each other.

Also, a plurality of guide hole units may be defined in a centralportion of the first moving mass 23. Also, each of the guide hole unitsmay include a plurality of holes 233. The plurality of guide hole unitsmay be defined in a line defined by bisecting the first moving mass 23in the front and rear direction or defined in left and right positionssymmetrical to each other with respect to the line defined by bisectingthe first moving mass 23 in the lateral direction.

The guide hole units may be portions on which the support 28 that willbe described later in detail is mounted. Thus, the first moving mass 23may stably move while being maintained in a horizontal state by thesupport 28. A single guide hole unit may be defined in a center of themoving mass 23. In this case, the first moving mass 23 may be verticallytilted while being reciprocated in the lateral direction to interferewith the support plate 21. Thus, at least two guide hole units may beprovided. In this embodiment, the two guide hole units are defined inleft and right sides of the moving mass 23.

Each of the guide holes 233 constituting the guide hole holes may have along hole shape with a long side and a short side. The long side of theguide hole 233 has a length d corresponding to the moving displacementof the moving mass 23. That is, when the horizontal oscillation istransmitted to the cabinet 11, the first moving mass 23 may be shaken bya length of the guide hole 233 in the lateral direction.

Although the first moving mass 23 is horizontally shaken in the lateraldirection, the first moving mass 23 may slightly oscillate in thevertical direction. When the vertical oscillation is transmitted to thefirst moving mass 23, the top surface of the first moving mass 23 maycollide with the top plate 12 to cause noise. To prevent this phenomenonfrom occurring, a buffer pad 234 may be separately attached to the topsurface of the first moving mass 23.

The buffer pad 234 may also be attached to the bottom surface of thefirst moving mass 23 to prevent a phenomenon in which a middle portionof the first moving mass 23 droops by a load from occurring or preventthe moving mass 23 from directly collide with the support plate 21 bythe vertical oscillation acting on the first moving mass 23. The bufferpad 234 may include a nonwoven fabric, a viscoelastic member, silicon,or the like. It is noted that buffer pad 234 may be mounted on at leastone surface of top and bottom surfaces of the second moving mass 23 thatwill be described later.

Also, one or plurality of buffer member holes 232 may be defined in thefirst moving mass 23, and the buffer member holes 232 will be describedbelow in detail with reference to the accompanying drawings. The buffermember holes 232 may also be defined in the second moving mass 24.

FIG. 10 is a view illustrating a buffer structure for the verticaloscillation of the first moving mass according to an embodiment, andFIG. 11 is a longitudinal cross-sectional view taken along line 11-11 ofFIG. 10. Referring to FIGS. 10 and 11, the buffer member hole 232 may bedefined in the first moving mass 23, and a buffer pin 235 may beinserted into the buffer member hole 232.

In detail, the buffer pin 235 may include a pin body 235 a having anouter diameter corresponding to a diameter of the buffer member hole232, an upper buffer part 235 b provided on an upper end of the pin body235 a, and a lower buffer part 235 c provided on a lower end of the pinbody 235 a. In more detail, at least the upper buffer part 235 b and thelower buffer part 235 c of the buffer pin 235 may be made of the samematerial as the buffer pad 234. Also, the lower buffer part 235 c mayhave an outer diameter greater than that of the pin body 235 a, and anupper end of the upper buffer part 235 b may be spaced apart from abottom surface of the top plate 12 and higher than the top surface ofthe first moving mass 23.

Also, in a state in which the buffer pin 235 is coupled to the firstmoving mass 23, the lower buffer part 235 c may be spaced apart from thetop surface of the support plate 21. Here, the upper buffer part 235 bmay be provided as a separate part having an outer diameter greater thana diameter of the buffer member hole 232 and coupled to the upper end ofthe pin body 235 a. Here, the lower buffer part 235 c may be integratedwith the pin body 235 a to form a single body. Alternatively, the upperbuffer part 235 b and the pin body 235 a may be provided in one body,and the lower buffer part 235 b may be provided as a separate member andcoupled to a lower end of the pin body 235 a.

As described above, when the buffer pin 235 is inserted into the buffermember hole 232, the upper and lower ends of the buffer member 235 maynot come into contact with the top plate 12 and the support plate 21when the vertical oscillation does not act on the first moving mass.That is, when the vertical oscillation acts on only the first movingmass 23, the upper and lower ends of the buffer pin 235 mayintermittently come into contact with the top plate 12 and the supportplate 21. It is noted that the structure of the buffer pin 235 may beequally applied to the second moving mass 24.

FIG. 12 is a cross-sectional view of a separation prevention structurefor preventing the moving mass from being separated from the supportplate while the laundry treating apparatus is carried. The separationprevention structure may be equally applied to the second moving mass aswell as the first moving mass.

Referring to FIG. 12, at least one through-hole 220 having a long-holeshape having the same shape as the guide hole (see reference numeral 233of FIG. 8) may be defined in the moving mass 22. That is, thethrough-hole 220 may have a long side and a short side, whichrespectively have the same length as the long side and the short side ofthe guide hole 233. In detail, the long side of the guide hole 233 mayhave a length d equal to that of the long side of the through-hole 220.

Also, a coupling member V such as a bolt may pass through thethrough-hole 220. Also, the coupling member V may pass through thethrough-hole 220 from the top surface of the moving mass 22 and theninserted to be fixed to the support plate 21. Also, a main body of thecoupling member V accommodated into the through-hole 220 may have thesame diameter as a guide boss (that will be described later) of thesupport 28 fitted into the guide hole 233. Also, a head of the couplingmember V may have an outer diameter greater than a length of the shortside of at least the through-hole 220 to prevent the moving mass 21 frombeing separated from the coupling member V during the oscillation.

According to the above-described structure, while the laundry treatingapparatus 10 on which the dynamic absorber 20 is mounted is carried,even though the laundry treating apparatus 10 is turned upside down orsideways, the moving mass 22 may not be separated from the support plate21. Also, since the long side of the through-hole 220 has the samelength as the long side of the guide hole 233, the moving mass 22 doesnot act as an obstacle while being shaken in the lateral direction toabsorb the oscillation of the cabinet 11. That is, the coupling member Vdoes not collide with the moving mass 22. This is done because themoving mass 22 is limited in maximum oscillation displacement in thehorizontal direction by the elastic damper 25, and the long side of thethrough-hole 220 has the length d greater than the maximum oscillationdisplacement of the moving mass 22.

FIG. 13 is a perspective view of the second moving mass according to anembodiment. Referring to FIG. 13, the second moving mass 24 according toan embodiment is provided for mainly absorbing the transient oscillationacting on the cabinet 11. In detail, the second moving mass 24 has amess less than that of the first moving mass 24 and is operated at arotational speed less than that (rpm) (or the rotation frequency) of thedrum in which the first moving mass 23 is operated.

Also, like the first moving mass 23, the second moving mass 24 may haverounded corners each of which has a rectangular shape and be provided asa single mass made of a metal material or have a structure in which aplurality of thin metal plates are laminated. Also, when the moving mass24 is manufactured by laminating a plurality of thin metal plates, theplurality of thin metal plates may be coupled to each other by the rivetpart 241 to form a single body. When a plurality of sliders 29 may bemounted on the bottom surface of the second moving mass 24, and aplurality of slider coupling holes 242 may be defined in portions onwhich the sliders 29 are mounted.

FIG. 14 is a top perspective view of the support according to anembodiment, FIG. 15 is a bottom perspective view of the support, FIG. 16is an exploded perspective view of the support, and FIG. 17 is alongitudinal cross-sectional view taken along line 17-17 of FIG. 14.Referring to FIGS. 14 to 17, the support 28 according to an embodimentis provided on the bottom surface of the moving mass for absorbing thecontinuous oscillation.

In detail, the support 28 is provided on the bottom surface of the firstmoving mass 23 to minimize an occurrence of frictional force when thefirst moving mass 23 oscillates in the lateral direction, therebymaximizing the absorption of the continuous oscillation at thehigh-speed rotation. In addition, the support 28 may prevent the firstmoving mass 23 from drooping by a self-load thereof and allow the firstmoving mass 23 to oscillate in the horizontal direction as far aspossible.

The support 28 may include a roller support part 282 fixed to thesupport mounting part 219 of the support plate 21 and a guide roller 281rotatably seated on the roller support part 282. The guide roller 281includes a roller 281 a and a roller shaft 281 b passing through acenter of the roller 281 a. The roller 281 a comes into line contactwith the bottom surface of the moving mass 23 to rotate together withthe first moving mass 23. Although the guide roller 281 is provided tominimize the frictional force generated between the first moving mass 23and the support 2, it is noted that a ball bearing that comes into pointcontact with the first moving mass 23 may be applied.

Also, the roller support part 282 may include a seating plate 282 aseated on the top surface of the support plate 21, at least a pair ofcoupling hooks 282 e respectively extending downward from front and rearends of the seating plate 282 a, an accommodation hole defined in acenter of the seating plate 282 a, and a plurality of guide bosses 282 bprotruding by a predetermined length from a top surface of the seatingplate 282 a. In detail, the coupling hooks 282 e are provided torespectively extend from front and rear ends of the seating plate 282 a,but are not limited thereto. For example, a plurality of coupling hooksmay be provided on each of the front and rear ends.

Also, two guide bosses 282 b are provided to respectively protrude fromleft and right edges of the seating plate 282 a, but are not limitedthereto. For example, one guide boss 282 b may be provided to protrudefrom each of the left and right edges. Also, the guide boss 282 b isinserted into the guide hole 233 of the first moving mass 23. Thus, thenumber of guide holes 233 corresponding to the number of guide bosses282 b may be provided. Also, when the first moving mass 23 oscillates inthe lateral direction, the guide boss 282 b may relatively move in thelateral direction within the guide hole 233. The guide boss 282 b mayhave a diameter corresponding to the length of the short side of theguide hole 233.

Also, the accommodation hole may include a roller shaft accommodationhole 282 d extending from the center of the seating plate 282 a in thefront and rear direction to accommodate the roller shaft 281 b and aroller accommodation hole 282 c extending from the center of the seatingplate 282 a in the lateral direction to accommodate the roller 281 a.

Also, as illustrated in FIG. 15, a shaft support rib 282 f may protrudefrom each of left and right edges of a bottom surface of the rollershaft accommodation hole 282 d. In detail, the pair of shaft supportribs 282 f extending from points facing each other may be provided onfront and rear end points of the roller accommodation hole 282 c tosupport portions of the front roller shaft 281 b and the rear rollershaft 281 b with respect to the roller 281 a, respectively. Asillustrated in FIG. 17, the roller shaft 281 b is supported by the shaftsupport ribs 282 f and also supported by the roller shaft support part219 b provided to be rounded in an arc shape on the support plate 21.

Also, a shake prevention rib 282 g extends from each of bottom surfacesof left and right ends of the roller accommodation hole 282 c. The pairof shake prevention ribs 282 g may be hooked on the left and right endsof the roller hole 219 a defined in the support plate 21 to prevent theseating plate 282 a from being shaken in the lateral direction. If theshake prevention ribs 282 g are not provided, fastening force of thepair of coupling hooks 282 e should be considerably large. However,since the shake prevention ribs 282 g are provided, it is sufficientthat the pair of coupling hooks 282 e is hooked on the support plate 21.Also, the phenomenon in which the seating plate 282 a is shaken in thelateral direction is prevented by the shake prevention ribs 282 g.

FIG. 18 is a top perspective view of an upper slider constituting aslider according to an embodiment, FIG. 19 is a bottom perspective ofthe upper slider, FIG. 20 is a top perspective view of a lower sliderconstituting the slider, FIG. 21 is a bottom perspective view of thelower slider, and FIG. 22 is a longitudinal cross-sectional view takenalong line 22-22 of FIG. 3. Referring to FIGS. 18 to 22, the slider 29according to an embodiment is mounted on the bottom surface of themoving mass for absorbing the transient oscillation. Thus, the slider 29may be provided on the bottom surface of the second moving mass 24. Indetail, the slider 29 has a structure in which an upper slider 30 and alower slider 31 are coupled to each other. The upper slider 30 and thelower slider 31 slidably move with respect to each other withpredetermined frictional attenuation.

The second moving mass 24 absorbs the transient oscillation generated atthe resonant point of the drum by the magnitude of the frictionalattenuation of the slider 29. Also, the transient oscillation absorptionregion (or oscillation absorption width) is determined by the magnitudeof the frictional attenuation and the mass of the second moving mass 24.In detail, the upper slider 30 may include an upper slider body 301having an approximately rectangular shape, a plurality of couplingprotrusions 302 protruding from four corners of a top surface of theupper slider body 301, and a plurality of slider rails 303 protrudingfrom a bottom surface of the upper slider body 301 and extending in alongitudinal direction of the upper slider body 301.

In detail, the plurality of coupling protrusions 302 may be insertedinto the plurality of slider coupling holes 242 defined in the secondmoving mass 24. The number of the slider coupling holes 242corresponding to the number of coupling protrusions 302 may be definedin the second moving mass 24. Also, the plurality of slider couplingholes 242 corresponding to the number and position of the couplingprotrusions 302 may form one slider coupling hole group. Also, aplurality of slider coupling hole groups may be defined in the secondmoving mass 24 so that the upper slider 30 is coupled to the bottomsurface of the second moving mass 24 at various positions.

The coupling protrusions may protrude from the four corners of the topsurface of the upper slider body 301, but are not limited thereto. Foranother example, one coupling protrusion may protrude from a center ofone edge of the top surface of the upper slider body 301, and also, thecoupling protrusion may protrude from each of two corners of the facingedge in a three point supporting manner. For further another example, atleast two coupling protrusions may be arranged in a row in a widthdirection or a longitudinal direction at the center of the top surfaceof the upper slider body 301.

Also, a pair of two slider rails 303 may be inserted into railaccommodation grooves 312 (that will be described later) defined in thelower slider 31. When the slider rails 303 are accommodated into therail accommodation grooves 312, the second moving mass 24 may be shakenin the horizontal direction in a phase opposite to that of theexcitation force generated by the rotational force of the drum on thesupport plate 21. Also, when the slider rails 303 are accommodated intothe rail accommodation grooves 312, the second moving mass 24 may beprevented from being shaken in the front and rear direction of thecabinet 11.

Although the two slider rails 303 are accommodated into the railaccommodation grooves 312, an embodiment of the present disclosure isnot limited thereto. For example, it is noted that at least three sliderrails 303 may be accommodated into the rail accommodation grooves 312.

Also, the lower slider 31 may have a rectangular shape with the samesize as the upper slider 30. In detail, the lower slider 31 may includea lower slider body 311 having the same shape as the upper slider body301, a rail accommodation groove 312 extending in the longitudinaldirection of the lower slider body 311 on the top surface of the lowerslider body 311, and a plurality of coupling protrusions 314 protrudingfrom a bottom surface of the lower slider body 311.

Here, a protruding length of each of the slider rails 303 of the upperslider 30 may be equal to or slightly greater than a recessed depth f ofeach of the rail accommodation grooves 312. Also, the recessed depth fof the rail accommodation groove 312 may be greater than a distancebetween the top surface of the second moving mass 24 and the bottomsurface of the top plate 12. In this case, while the laundry treatingapparatus 10 is carried, even though the laundry treating apparatus 10is turned upside down or tilted, the slider rail 303 may be preventedfrom being separated from the rail accommodation groove 312.

In more detail, the plurality of coupling protrudes 314 may have thesame shape and number as the plurality of coupling protrusions 314provided on the upper slider 30 on the same formation position. Thus,duplicated description of the plurality of coupling protrusions 314provided on the lower slider 31 will be omitted. Of course, theplurality of slider coupling holes 218 b into which the plurality ofcoupling protrusions 314 are inserted may be defined in the supportplate 21, particularly, the second forming part 217 b of the supportplate 21. Also, the plurality of slider coupling holes 218 b may bedefined in a plurality of positions constituting groups having numberscorresponding to the number of lower sliders 31.

Also, the plurality of rail accommodation grooves 312 may be arranged inparallel to each other with a width less than that of the slider body311. That is, the rail accommodation groove 312 may be partitioned intothe plurality of rail accommodation grooves by the partition wall 313.In this embodiment, although the two rail accommodation grooves 312 arearranged in parallel to each other in the width direction of the sliderbody 311, an embodiment of the present disclosure is not limitedthereto. For example, at least three rail accommodation grooves may bearranged in parallel to each other. Of course, a single railaccommodation groove 312 may be defined without providing the partitionwall 313.

Also, two or more slider rails 303 may be accommodated in each of therail accommodation grooves 312, and at least two slider rails 303 maycome into contact with front and rare edges of the rail accommodationgroove 312. That is, the frontmost rail of the at least two slider rails303 accommodated into the rail accommodation groove 312 may come intocontact with the front edge of the rail accommodation groove 312, andthe rear rail may come into contact with the rear edge of the railaccommodation groove 312. For example, when three slider rails areprovided, two slider rails may come into contact with front and rearsurfaces of the rail accommodation groove 312, the rest may be providedat a center of the rail accommodation groove 312.

As described above, since the front and rear surfaces and the bottomsurface of the at least two slider rails 303 come into contact with thefront and rear surfaces and the bottom surface of the rail accommodationgroove 312, when the second moving mass 24 moves in the lateraldirection (the longitudinal direction of the slider), the attenuationdue to the frictional force may act to absorb the transient oscillation.

The frictional force generated in the slider 29 acts as attenuation ofthe second moving mass 24. Also, the attenuation of the second movingmass 24 may act as a variable for determining the oscillationdisplacement of the transient oscillation. Also, a frictionalcoefficient of the frictional force determines the magnitude of theattenuation. The more the attenuation (or an attenuation value)increases, the more the transient oscillation absorption capacity of thedynamic absorber 20 is improved.

Of course, since the elastic damper 23 has the attenuation function forabsorbing the transient oscillation as well as the elastic (orrigidity), although it affects the improvement of the transientoscillation, it is significantly smaller than the attenuation due to thefriction. Thus, the elastic damper 23 may be damper that mainly affectsthe continuous oscillation transmitted to the cabinet 11 by the dynamicabsorber 20.

In addition, it is possible to obtain an effect of preventing the secondmoving mass 24 from being shaken in the front and rear direction (thefront and rear width direction of the slider) of the laundry treatingapparatus 10. Also, the upper slider 30 and the lower slider 31 may bemolded by using engineering plastic made of polyoxymethylene (POM).Also, since a noise is generated when the plastic made of the samematerial moves while coming into contact therewith, a lubricant such asgrease may be applied to the rail accommodation groove 312.

The rail accommodation groove 312 has a length greater than that of theslider rail 303 so that the upper slider 30 is reciprocated in thelateral direction on the lower slider 31. This is done because, if theupper slider 30 does not move in the lateral direction on the lowerslider 31, the second moving mass 24 does not oscillate in a phaseopposite to the oscillation of the cabinet. In detail, a value obtainedby subtracting the length of the slider rail 303 from the length of therail accommodation groove 312 in the lateral direction is equal to orgreater than the moving displacement of the second moving mass 24.

FIG. 23 is a top perspective view of a second elastic damper accordingto an embodiment, and FIG. 24 is a bottom perspective view of the secondelastic damper. Referring to FIGS. 23 and 24, the dynamic absorber 20according to an embodiment includes a second elastic damper 27 mountedon the side surface of the moving mass for absorbing the transientoscillation.

The second elastic damper 27 constituting the dynamic absorber 20according to an embodiment may be provided on each of left and rightedges of the second moving mass 24. In detail, when the second movingmass 24 is shaken in the lateral direction, each of the left and rightedges of the second moving mass 24 may collide with the second elasticdamper 27. Here, while the second elastic damper 27 is elasticallydeformed, the second elastic damper 27 absorbs an impact of the secondmoving mass 24.

Also, although two second elastic dampers 27 are provided on each of theleft and right edges of the second mass 24, an embodiment of the presentdisclosure is not limited thereto. For example, at least three secondelastic dampers 27 may be provided each of the left and right edges ofthe second mass 24. For example, the second elastic dampers 27 may beprovided on the rear ends, central portions, and front ends of bothedges of the second moving mass 24, respectively.

Also, each of the second elastic dampers 27 may have a hexahedral shapehaving a front surface 271, a rear surface 274, side surfaces 272, a topsurface 273, and a bottom surface 279. Also, an inclined portion 275 maybe provided at a corner at which the front surface 271 and the topsurface 273 meet each other, or the corner may be rounded.

Also, a rounded portion 276 or an inclined portion may also be providedat a corner at which the bottom surface 279 and the rear surface 274meet each other. Since the inclined portion 275 is provided, when thehorizontal force of the second moving mass 24 is applied to the frontsurface 271, the second elastic damper 27 may be deformed in shape toprotrude and thereby to be prevented from interfering with the top plate12.

Also, since the rounded portion 276 is provided, when the horizontalforce of the second moving mass 24 is applied to the front surface 271,a corner of the rear surface of the second elastic damper 27 mayprotrude to be prevented from interfering with a corner of the side edgeof the moving mass seating part 241. Also, the second elastic damper 27may further include an elastic groove 277 recessed upward from thebottom surface 279 and a coupling arm 278 protruding from the bottomsurface 279 and fitted into the coupling slit 216.

In detail, when the second moving mass 24 presses the bottom surface ofthe second elastic damper 27 while being shaken in the horizontaldirection, the elastic groove 277 may be provided to allow the secondelastic damper 27 to be easily deformed to wall absorb the impact. Theelastic groove 277 may be defined as an impact absorption groove. Here,the elastic groove 277 may be recessed with a predetermined width inleft/right and front/rear direction and a predetermined depth upward.

The elastic groove 277 may be defined in a position closer to the frontsurface 271 than the rear surface 274 to facilitate the impactabsorption of the second moving mass 24. Also, the elastic groove 277may have a structure in which the elastic groove 277 is opened in thetop surface of the second elastic damper 27 and recessed downward inaddition to a structure in which the elastic groove 277 is opened in thesecond elastic damper 27 and recessed upward. For example, the elasticgroove 277 may be opened in the inclined portion 275 and recessed by apredetermined depth downward.

Also, the coupling arm 278 may include an extension end 278 a extendingby a predetermined length from the bottom surface 279 and a hookprotrusion 278 b extending from a side edge of an end of the extensionend 278 a. That is, the coupling arm 278 may have a longitudinalcross-section with an inverted T shape, but is not limited thereto. Whenthe coupling arm 278 has the longitudinal cross-section with theinverted T shape, since the coupling slit 216 may have a T or I shape,the coupling arm 278 may be more easily inserted.

In detail, to couple the coupling arm 278 to the coupling slit 216, thesecond elastic damper 27 is inclined tilted to allow an end of the hookprotrusion 278 b to be provided on the short side of the coupling slit216. Here, the extension end 278 a is provided on the long side of thecoupling slit 216. In this state, the second elastic damper 27 movesalong the long side of the coupling slit 216 so that the second elasticdamper 27 becomes a horizontal state while the hook protrusion 278 b ispushed to be inserted into the short side of the coupling slit 216.Also, when the second elastic damper 27 completely becomes thehorizontal state, the second elastic damper 27 may be completelyinserted into the coupling slit 216.

Also, to prevent the second elastic damper 27 from being shaken in thevertical direction in the state of being coupled to the support plate21, the extension end 278 a may have a length corresponding to athickness of the support plate 21. That is, a distance between thebottom surface 279 and the upper end of the hook protrusion 278 b may beequal to the thickness of the support plate 21. Also, the coupling arm278 may be provided at a position closer to the rear surface 274 thanthe front surface 271 of the second elastic damper 27, but is notlimited thereto.

FIG. 25 is a top perspective view of the first elastic damper accordingto an embodiment, FIG. 26 is a bottom perspective view of the firstelastic damper, and FIG. 27 is a longitudinal cross-sectional view takenalong line 27-27 of FIG. 25. Referring to FIGS. 25 to 27, the firstelastic damper 26 according to an embodiment may be mounted on the sidesurface of the moving mass for absorbing the continuous oscillation. Indetail, the first elastic damper 26 may include a side support parthaving the same as the second elastic damper and a bottom support parthorizontally extending from the side support part.

Also, although two first elastic dampers 26 are provided on each of theleft and right edges of the first mass 23, an embodiment of the presentdisclosure is not limited thereto. For example, at least three firstelastic dampers 26 may be provided each of the left and right edges ofthe first mass 23. For example, the first elastic dampers 26 may beprovided on the rear ends, central portions, and front ends of bothedges of the first moving mass 23, respectively.

Also, the side support part of the first elastic damper 26 may have thesame shape as the second elastic damper 27. That is, the side supportpart of the first elastic dampers 26 may have a hexahedral shape havinga front surface 261, a rear surface 264, side surfaces 262, a topsurface 263, and a bottom surface 269. Also, an inclined portion 265 maybe provided at a corner at which the front surface 261 and the topsurface 263 meet each other, or the corner may be rounded.

Also, the first elastic damper 26 may further include an elastic groove266 and a coupling arm 268. In detail, the elastic groove 266 may berecessed by a predetermined depth downward from the top surface 263 orrecessed by a predetermined depth upward from the bottom surface 269.

Also, the coupling arm 268 may include an extension end 268 a and a hookprotrusion 268 b. A method for inserting the coupling arm 268 into thecoupling slit 216 may be equal to that for inserting the coupling arm278 into the coupling slit 216. The bottom support part may be a portionfor supporting an edge of the bottom surface of the first moving mass 23and include a horizontal part 269 a and a vertical part 269 b.

In detail, the horizontal part 269 a may extend horizontally from thefront surface 261, and the vertical part 269 b may extend downward froman end of the horizontal part 269 a. Also, the horizontal part 269 a maybe designed to extend horizontally from a position spaced upward from alower end of the front surface 261 so as to be elastically deformed.

The first moving mass 23 may have a mass that is relatively larger thanthat of the second moving mass 24 and be operated to rotate at a highspeed. That is, the first moving mass 23 oscillate at a high frequencyto reduce the continuous oscillation generated when the drum ismaintained at the maximum speed. In this case, the first moving mass 23may oscillate in a vertical direction as well as a horizontal direction.When the first moving mass 23 oscillates in the vertical direction, theleft and right ends of the first moving mass 23 may come into contactwith the support plate 21 to generate noise. To present this phenomenonfrom occurring, the bottom support part may support the bottom surfacesof the left and right edges of the first moving mass 23.

Alternatively, when the first moving mass 23 is maintained in thehorizontal state by the support 28, the second elastic damper 27 insteadof the first elastic damper 26 may be provided on the side surface ofthe first moving mass 23. Ideally, it is advantageous in terms oflowering the frictional attenuation that the first moving mass 23 doesnot come into contact with the horizontal part 269 a while being shakenin the lateral direction. However, when the first moving mass 23oscillates in the horizontal state, the first moving mass 23 ismaintained in the state of being spaced apart from the horizontal part269 a, and only when the horizontal state of the first moving mass 23 isbroken, the first moving mass 23 may come into contact with thehorizontal part 269 a to achieve both of the two purposes.

Hereinafter, a method for effectively absorbing the transientoscillation and the continuous oscillation generated in the cabinet 11through the dynamic absorber 20 to improve the oscillation will bedescribed. Equation 1 below is a dimensionless response formula showingthe behavior of the dynamic absorber 20 with respect to the oscillationgenerated when the drum having the eccentric load rotates.

$\begin{matrix}{Y = \sqrt{\frac{\left( {2\zeta \; r} \right)^{2} + \left( {r^{2} - \beta^{2}} \right)^{2}}{{\left( {2\zeta \; r} \right)^{2}\left( {r^{2} - 1 + {µ\; r^{2}}} \right)^{2}} + \left\lbrack {{µ\; r^{2}\beta^{2}} - {\left( {r^{2} - 1} \right)\left( {r^{2} - \beta^{2}} \right)}} \right\rbrack^{2}}}} & \left( {{Equation}\mspace{14mu} 1} \right)\end{matrix}$

wherein:

${r = \frac{\omega}{\omega_{p}}},{µ = \frac{m_{a}}{m_{p}}},{\beta = \frac{\omega_{a}}{\omega_{p}}},{\zeta = \frac{c_{a}}{2m_{a}\omega_{p}}},$

andwherein

Y: Dimensional oscillation displacement (or amplitude) of moving mass

r: Operating speed ratio (or operating frequency ratio)

ω: Rotational speed (or rotation frequency) of drum

ωa: Natural oscillation (or natural frequency) of moving mass

ωp: Natural oscillation (or natural frequency) of laundry treatingapparatus

β: Oscillation ratio (or frequency ratio)

μ: Mass ratio

ma: Mass of moving mass

mp: Mass of laundry treating apparatus

ζ: Attenuation ratio

ca: Attenuation of moving mass

A dimensionless response formula of the dynamic absorber is expressed byusing a mass ratio, an oscillation ratio, and attenuation ratio asvariables. Also, although the mass ratio is strictly defined as the massratio of the moving mass 22 to the mass of the laundry treatingapparatus 10, it may be regarded as the mass ratio of the dynamicabsorber 20 to the mass of the laundry treating apparatus 10. This isdone because the mass is regarded as a portion of the mass of thelaundry treating apparatus 10 and has little effect on determining thetotal mass of the laundry treating apparatus 10 because the componentsof the dynamic absorber 20 except for the moving mass 22 are fixed tothe laundry treating apparatus 10. Also, this is done because the upperslider 30 has a mass which is negligible with respect to the mass of themoving mass 22. Thus, it is noted that the mass ratio may be interpretedas the mass ratio of the dynamic absorber 20. Also, it is noted that theoscillation ratio and the attenuation ratio may be defined orinterpreted as the oscillation ratio of the dynamic absorber 20 and theattenuation ratio of the dynamic absorber 20, like the mass ratio.

A shape of the response curve shown by the response formula isdetermined by the mass ratio, the oscillation ratio, the attenuationratio, and oscillation absorption capacity of the dynamic absorber 20 isdetermined by these variables. That is, when the rotational speed ratioof the drum increases in a state in which the mass ratio, theoscillation ratio, and the attenuation ratio, which are variables of theresponse formula, a dimensionless amplitude of the dynamic absorber 20may be calculated, and thus, the calculated dimensionless value may beregarded as an oscillation displacement of the cabinet 11.

Here, the mass ratio of the dynamic absorber 20 is a design variable fordetermining an oscillation absorption region for absorbing the transientoscillation, and the oscillation ratio (or the frequency ratio) and theattenuation ratio are variables for determining an oscillationdisplacement of secondary transient oscillation after the attenuation.In detail, when the moving mass (the second moving mass in thisspecification) for absorbing the transient oscillation of the dynamicabsorber 20 is operated at the resonant point, two transientoscillations, which are significantly less than the oscillationdisplacement when the transient oscillation occurs, may occur.

Also, a distance between the two secondary transient oscillations isdefined as an oscillation absorption region or width, and a size of theoscillation absorption region may vary according to the mass ratio.Also, the oscillation displacements, i.e., peak points of the twosecondary transient oscillations may vary by adjusting the oscillationratio and the attenuation ratio. For reference, the two secondarytransient oscillations are displayed as two peak points in which thedimensionless amplitude value increases and then decreases. A distancebetween the two peak points is interpreted as the oscillation absorptionregion and varies by adjusting the mass ratio.

The resonant frequency generated in the transient oscillation may varyaccording to a size, mass, product variation, and eccentricity of thelaundry (load) put into the drum in the laundry treating apparatus. Insuch a situation, to effectively absorb the transient oscillation of thelaundry treating apparatus 10 to improve the oscillation, theoscillation absorption region has to be equal to or greater than theresonant frequency region.

Here, the oscillation absorption region of the dynamic absorber 20 maybe defined as a width between a rotation frequency at which the secondmoving mass 24 starts to move in a direction opposite to the excitationforce generated when the drum rotates to be accelerated and a rotationfrequency at which the oscillation is reduced by the excitation force asthe rotational speed of the drum increases to allow the second movingmass 24 to be stopped.

Here, a time point at which the moving mass starts to move may bedefined as a time point at which the moving mass oscillates in a phasedifferent from the oscillation phase of the cabinet 11 or the supportplate 21. In other words, a time point at which the moving mass isstopped may be defined as a time point at which the moving massoscillates to move in the same phase as the oscillation phase of thecabinet 11 or the support plate 21.

Also, a factor that determines the size of the transient oscillationabsorption region of the dynamic absorber 20 is the mass ratio. That is,the more the mass ratio increases, the more the transient oscillationabsorption region is widened, and the more the mass ratio decreases, themore the transient oscillation absorption region is narrowed. In otherwords, the more the mass of the second moving mass 24 increases, themore the transient oscillation is absorbed in a wide region.

To increase the oscillation absorption region, the mass ratio mayincrease, but an inner space of the cabinet 11 on which the dynamicabsorber 20 is mounted is limited. In detail, since the dynamic absorber20 is mounted on the top surface of the cabinet 11 and covered by thetop plate 12, there is a restriction that the dynamic absorber 20infinitely increases in surface area and thickness.

Theoretically, if the mass of the dynamic absorber 20, particularly, themass of the moving mass 21 is equal to the total mass of the laundrytreating apparatus 10 on which the dynamic absorber 20 is mounted, thetransient oscillation may be perfectly absorbed. However, if the mass ofthe moving mass 21 excessively increases, since there is a disadvantagethat the load of the laundry treating apparatus 10 is excessively large,it is difficult to move and install the moving mass 21, and a droopingphenomenon due to a self-weight of the second moving mass 21 may occur.Above all, there is a limit to increase the load (or the mass) of thesecond moving mass 21 due to the restriction of the installation spacein the cabinet 11. Also, when only the second moving mass 21 isinstalled, the transient oscillation may be improved, but the continuousoscillation may not be absorbed. That is, there is a limitation that onemoving mass does not absorb both the transient oscillation and thecontinuous oscillation.

FIG. 28 is a graph illustrating oscillation displacement of the laundrytreating apparatus on which the dynamic absorber including only themoving mass for absorbing the transient oscillation is mounted. Ahorizontal axis of the graph represents the rotational speed (rpm), anda vertical axis represents the oscillation displacement of the cabinet.The rotational speed may be regarded as the same as the rotationfrequency.

Referring to FIG. 28, the graph A is a graph of oscillation displacementof the cabinet measured in the laundry treating apparatus on which thedynamic absorber 20 is not mounted, and the graph B is a graph ofoscillation displacement of the cabinet measured in the laundry treatingapparatus on which the moving mass for absorbing the transientoscillation, which has a predetermined mass ratio.

First, a case in which the dynamic absorber is not mounted will bedescribed. As the drum into which laundry to be rinsed or dehydrated isput starts to rotate and then increases in rotational speed, horizontalexcitation force is generated by rotation of the eccentric laundry putinto the drum. Also, the horizontal oscillation displacement of thecabinet increases by the excitation force. Also, when the rotationalspeed reaches the rotational speed of the drum, transient oscillation ofthe cabinet occurs by resonance. In the graph, a resonant point at whichthe transient oscillation occurs is determined as a range between about800 rpm to about 1000 rpm. Also, when the rotational speed of the drumexceeds the resonant frequency, the oscillation gradually decreases.Also, the cabinet experiences the continuous oscillation in which theoscillation displacement value hardly changes in a range in which thedrum is maintained at the maximum speed.

In the case in which the dynamic absorber 20 is mounted, as the drumincreases in rotational speed, the cabinet 11 increases in oscillationdisplacement. Also, in the low-speed range in which the dynamic absorberdoes not start, the behavior of the oscillation displacement graph isnot significantly different from the case in which the dynamic absorberis not mounted. However, when the rotation frequency (or rotationalspeed) of the drum falls within a frequency range at which the dynamicabsorber, i.e., the moving mass starts to operate, the moving massstarts to move. As a result, the increasing oscillation displacement ofthe cabinet rapidly decreases, and the oscillation displacement of thecabinet, which rapidly decreases as the rotational speed of the drumincreases, gradually increases again. That is, it is seen that thetransient oscillation generated when the dynamic absorber is not mountedis absorbed by the dynamic absorber.

Then, when the rotational speed of the drum continuously increases, andthe oscillation displacement of the cabinet increases up to a time pointat which the oscillation of the moving mass is stopped, and then, therotational speed of the drum is out of the oscillation absorption regionof the dynamic absorber, the moving mass is stopped. In detail, therotational speed of the drum exceeds the resonant frequency, theoscillation due to the excitation force is weakened, and thus, theoscillation displacement of the cabinet decreases. Thus, when therotational speed of the drum is out of the transient oscillationabsorption region of the dynamic absorber 20, the oscillationdisplacement of the cabinet decreases and then is maintained to thedisplacement in the continuous oscillation.

Here, in the graph B, it is seen that, since the transient oscillationis absorbed by the dynamic absorber 20, two inflection points a and bhaving an oscillation displacement less than that in the transientoscillation are formed. The oscillation at the two inflection points maybe defined as secondary transient oscillation. Also, the two inflectionpoints a and b may correspond to two peak points appearing in theresponse curve. A distance W between the two inflection points may bedefined as the oscillation absorption region or the oscillationabsorption width.

In detail, the two secondary transient oscillations may occur at each ofan initial point and the last point, respectively. The front secondarytransient oscillation is oscillation occurring because the moving massabsorbs the oscillation that is increasing as the moving mass starts tomove. Also, the rear secondary transient oscillation is oscillationoccurring because the behavior of the moving mass is stopped, and thus,the cabinet behaves under the same condition as the case in which thedynamic absorber is not mounted.

Also, when the oscillation absorption region is widened by adjusting themass ratio, the oscillation displacement of the secondary transientoscillation may be more reduced, and the time point at which the frontsecondary transient oscillation occurs may be advanced to the low-speedrange. Thus, stability of the washing machine may be improved whencompared to the case in which the transient oscillation occurs at thehigh-speed range. Also, the oscillation displacement at the rearsecondary transient oscillation may be controlled to be significantlylower than that at the front secondary transient oscillation byadjusting the oscillation ratio and the attenuation ration.

Here, the reason in which the two secondary transient oscillations occuris because the oscillation absorption amount is largest at the resonantpoint of the drum. That is, since the moving mass 21 is designed toabsorb the transient oscillation as much as possible at the resonantpoint at which the transient oscillation occurs by allowing the movingmass 21 to maximally oscillate in the direction opposite to theoscillation direction generated by the excitation force, it is naturalthat the secondary transient oscillation occurs at both ends of theoscillation absorption region.

FIG. 29 is a graph illustrating oscillation displacement of the laundrytreating apparatus on which the dynamic absorber is mounted according toan embodiment. In detail, a graph D is a graph showing the oscillationdisplacement of the cabinet according to the rotational speed of thedrum in the state in which the dynamic absorber is not mounted andcorresponds to the graph A of FIG. 28.

A graph E is a graph showing the vibration displacement of the cabinetwhen only the moving mass corresponding to the first moving mass, i.e.,the moving mass for absorbing the continuous oscillation is mounted.Also, a graph F is a graph showing the vibration displacement of thecabinet when the dynamic absorber 20 according to an embodiment, i.e.,both the moving mass for absorbing the continuous oscillation and themoving mass for absorbing the transient oscillation are mounted.

To design an oscillation pattern of the cabinet such as the graph E,first only the first moving mass 23 is mounted to obtain the oscillationdisplacement of the cabinet. That is, a mass ratio, an oscillationratio, and an attenuation ratio of the first moving mass are adequatelyset in consideration of a size of the support plate 21, a distancebetween the support plate 21 and the top plate 12, and a desiredcontinuous oscillation reduction amount.

Thus, the oscillation displacement of the cabinet 11 is shifted from thegraph D to the graph E as illustrated in the drawing. In the graph E, itis seen that the continuous oscillation displacement is reduced by about200 micrometers from t1 to t2 by the first moving mass. Here, it is seenthat the transient oscillation displacement is reduced, although notlarge, by about 100 micrometers from h1 to h2 by mounting the firstmoving mass, and also, the transient oscillation generation point movesto the low-speed range. It is seen that the first moving mass has nomajor effect on the reduction of the transient oscillation because it isa main target to absorb the continuous oscillation rather than thetransient oscillation.

In this state, the first moving mass 23 is included as a portion of themass of the laundry treating apparatus, and the mass ratio, theoscillation ratio, and the attenuation ratio of the second moving mass24 adequately change to determine an optimal mass by imputing theresultant values into the response formula. Also, when the oscillationdisplacement of the cabinet 11 is measured in the state in which thesecond moving mass 24 is mounted, the graph E is shafted to the form ofthe graph F.

That is, it is seen that the oscillation pattern changes from the graphD when the dynamic absorber 20 according to an embodiment is not mountedto the graph F when the dynamic absorber 20 is mounted. In the graph F,the transient oscillation occurring between about 800 rpm to about 900rpm is absorbed by the operation of the second moving mass 24 togenerate two transient oscillations having a small oscillationdisplacement. Also, the peak point of the rear secondary transientoscillation of the two secondary transient oscillations may be furtherreduced by adequately adjusting the mass ratio, the oscillation ratio,and the attenuation ratio.

Also, it is seen that the continuous oscillation is reduced from t1 tot3 by the first moving mass 23. Also, since the continuous oscillationis reduced from t2 to t3, it is seen that the second moving mass 24contributes, although not large, somewhat to absorb the continuousoscillation.

Since the support plate on which the first moving mass 23 and the secondmoving mass 24 are seated is limited in size, a mass ratio of the firstmoving mass 23 to the second moving mass 24 has to be adequatelyadjusted from the maximum mass of the moving mass, which corresponds tothe total size of the moving mass accommodation part 214 provided on thesupport plate 21. Also, since the mass of the first moving mass 23 forabsorbing the continuous oscillation has to be greater than that of thesecond moving mass 24 for absorbing the transient oscillation, it islimited to increase the transient oscillation absorption width, which iscapable of being covered by only the second moving mass 24 itself.

To overcome this limitation, the behavior region of the second movingmass 24 and the behavior region of the first moving mass 23 maypartially overlap each other to allow the first moving mass 23 topartially contribute the increase of the transient oscillationabsorption width. As a result, the oscillation improvement efficiency ofthe cabinet 11 may be maximized.

Referring to the graph 29, when the drum starts to rotate and then isgradually accelerated, the oscillation of the cabinet 11 graduallyincreases by the excitation force generated by the eccentric load putinto the drum. Also, when the rotational speed of the drum increasessomewhat (about 800 rpm in the drawings), the lateral behavior (oroscillation) of the second moving mass 24 starts. Also, the secondmoving mass 24 largely oscillates at the resonant point at which thetransient oscillation occurs to absorb the transient oscillation. Thus,the front secondary transient oscillation (a peak point k) occurs, andthe oscillation displacement of the cabinet 11 decreases and thenincreases again.

Here, the movement of the first moving mass 23 starts at a point atwhich the movement of the second moving mass 24 is ended, i.e., at apoint of approximately 950 rpm in the drawing. Also, the second movingmass 24 is stopped at a range of approximately 1050 rpm to 1100 rpm, andthereafter, only the first moving mass 23 moves. Thus, the first movingmass 23 is contributed, although not large, to absorb the transientoscillation somewhat at the point at which the rear secondary transientoscillation occurs. As a result, the rare secondary transientoscillation (peak point k2) is not only disappeared almost, but also thetransient oscillation area is widened.

In the drawings, W1 represents a transient oscillation absorption region(a section in which the second moving mass moves), W2 represents acontinuous oscillation absorption region (a section in which the firstmoving mass moves), and W3 represents an overlapping region (a sectionin which the first and second moving masses move together).

To obtain the above-described result, i.e., the oscillation pattern ofthe cabinet, a design condition of the dynamic absorber 20 is set byusing the response formula shown in Equation 1 above, and the dynamicabsorber 20 is manufactured under the set condition to directly measureoscillation and thereby to obtain following design conditions. First,considering a design variable region for improving the continuousoscillation, the first moving mass 23 has a mass ratio of about 4% toabout 10% of the mass of the drum and laundry contained therein, anoscillation ratio (or frequency ratio) of about 0.8 to about 1.5 of theRPMs of the drum, and an attenuation of about 0% to about 20% of theoscillation displacement of the laundry treatment apparatus.

When the mass ratio of the first moving mass 23 is less than about 4%,since an oscillation absorption width that is capable of being coveredby the first moving mass 23 is too narrow, the overlapping region withthe second moving mass 22 is eliminated to cause a limitation in whichthe second moving mass 22 does not help the absorption of the transientoscillation by the second moving mass 22. In addition, a limitation inwhich the continuous oscillation generated in the region beyond thecoverable oscillation absorption region is not absorbed may occur. Onthe other hand, the maximum value of the mass ratio of the first movingmass 23 may be set to about 10% by an internal spatial limit of thelaundry treating apparatus 10 on which the dynamic absorber 20 ismounted and the total weight limit of the laundry treating apparatus 10.

Also, since the continuous oscillation generated in the laundry treatingapparatus 10 frequently occurs in a range of approximately 900 rpm toapproximately 1300 rpm, the first moving mass has to be designed toabsorb the continuous oscillation generated in the abovementionedregion. However, when the oscillation ration of the first moving mass 23is less than about 0.8 or exceeds about 1.5, since the targetoscillation absorption region is out of the section in which thecontinuous oscillation is generated, resulting in a failure to absorbthe continuous oscillation.

First, considering a design variable region for improving the transientoscillation, the second moving mass 24 has a mass ratio of about 2% toabout 5%, an oscillation ratio of about 0.5 to about 1, and anattenuation of about 20% to about 50%. When the mass ratio of the secondmoving mass 24 is less than about 2%, like the case of setting the massratio of the first moving mass 23, the oscillation absorption width isexcessively narrowed, and thus, a region in which the transientoscillation is not absorbed may occur. Also, due to the spatial limit inthe laundry treating apparatus and the weight limit of the laundrytreating apparatus, the maximum mass ratio has to be set to about 5% orless.

Also, the mass ratio of the second moving mass 24 to the first movingmass 23 may be set to about 40% to about 60%. It is important toadequately set the mass ratio of each of the first moving mass 23 andthe second moving mass 24 in the state in which the space in the cabinetof the laundry treating apparatus 10 on which the dynamic absorber 20 ismounted is limited, particularly, an area of the support plate 21 and adistance between the support plate 21 and the top plate 12 arepreviously set.

When the mass ratio of the second moving mass 24 to the first movingmass 23 is set to less than about 40%, the continuous oscillationabsorption capacity is improved, but the rotational speed region inwhich the transient oscillation is not absorbed may occur. On the otherhand, when the mass ratio of the second moving mass 24 to the firstmoving mass 23 exceeds about 60%, the transient oscillation absorptioncapacity is improved, but the natural frequency of the first moving mass23 increases due to the reduction in mass of the first moving mass 23.As a result, the frequency ratio of the first moving mass 23 increases,and the rotational speed region, in which the continuous oscillation isnot absorbed because the continuous oscillation absorption region movesto a high-frequency region, i.e., the high-speed region, may occur. Inaddition, when the continuous oscillation absorption region moves to thehigh-speed region, the overlapping region in which the movement regionof the second moving mass 24 and the movement region of the first movingmass 23 overlap each other may be lost.

Also, the oscillation ratio and the attenuation ratio of each of thefirst moving mass 23 and the second moving mass 24 may be determined bya combination of the elastic modulus and attenuation of the elasticdamper 25 and the elastic modulus and attenuation of the support 28 andthe slider 29. For example, the hardness (or compressive strength) ofthe first elastic damper 26 may be set within a range of about 30 toabout 60 MPa under the condition of being manufactured in theabove-described shape. Also, the hardness of the second elastic damper27 may be set within a range of about 20 to about 50 MPa under thecondition of being manufactured in the above-described shape. Also, aroller or a ball bearing may be applied to the support 28 to minimizethe frictional force, and the slider 29 may generate appropriate kineticfrictional force for covering the set transient oscillation absorptionregion.

The laundry treating apparatus including the above-describedconstituents according to the embodiment has following effects. First,the dynamic absorber according to the embodiment may be provided in thelaundry treating apparatus to effectively absorb the oscillation havingvarious forms, which is generated in the cabinet of the laundry treatingapparatus. That is, the moving mass for absorbing the transientoscillation and the moving mass for absorbing the continuous oscillationmay be respectively provided to absorb both the transient oscillationgenerated in a low frequency (low-speed rotation) region and thecontinuous oscillation generated in a high frequency (high-speedrotation) region.

Second, since the dynamic absorber is designed so that the latter halfin oscillation of the moving mass absorbing the transient oscillationand the first half in oscillation of the moving mass absorbing thecontinuous oscillation overlap each other, the moving mass absorbing thecontinuous oscillation may be partially contributed to the absorption ofthe transient oscillation to increase the transient oscillationabsorption width. That is, it may be advantageous to reduce theoscillation displacement of the secondary transient oscillationgenerated in the latter half of the two secondary transient oscillationshaving small oscillation displacement occurring after the transientoscillation absorption.

Third, since the latter half of the transient oscillation absorptionregion and the first half of the continuous oscillation absorptionregion overlap each other, the oscillation displacement of the secondarytransient oscillation may be significantly reduced, and thus, theoscillation displacement of the continuous oscillation may be reduced toimprove the continuous oscillation absorption capability.

The present disclosure has been proposed to improve the above-describedlimitations. In one embodiment, a laundry treating apparatus includes: acabinet; a drum accommodated in the cabinet; and a dynamic absorberprovided to absorb oscillation of the cabinet, wherein the dynamicabsorber includes: a first moving mass movably disposed on the supportplate to absorb oscillation transmitted to the cabinet; and a secondmoving mass movably disposed on the support plate to absorb oscillationtransmitted to the cabinet, wherein each of the first and second movingmasses includes a single mass made of a metal material or a mass inwhich a plurality of thin metal plates are coupled to overlap eachother, and the first moving mass has a mass greater than that of thesecond moving mass.

In another embodiment, a laundry treating apparatus comprises a cabinet;a drum accommodated in the cabinet; and a dynamic dampener provided todampen oscillations of the cabinet, wherein the dynamic dampenerincludes: a first mass body provided to move relative to the cabinet todampen first oscillations transmitted to the cabinet; and a second massbody provided to move relative to the cabinet to dampen secondoscillation transmitted to the cabinet, wherein the first mass body hasa greater mass than the second mass body.

In yet another embodiment, a laundry treating apparatus comprises acabinet; a drum accommodated in the cabinet; and a dynamic dampenerprovided to dampen oscillation of the cabinet, wherein the dynamicdampener includes: a first mass body provided to move relative to thecabinet to dampen first oscillations transmitted to the cabinet; and asecond mass body provided to move relative to the cabinet to dampensecond oscillation transmitted to the cabinet, wherein a length of thefirst mass body in a direction of relative motion for the first massbody corresponds to a length of the second mass body in a direction ofrelative motion for the second mass body, and a width of the first massbody in a direction crossing the direction of the relative motion forthe first mass body is greater than a width of the second mass body in adirection crossing the direction of the relative motion for the secondmass body.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the disclosure. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

What is claimed is:
 1. A laundry treating apparatus comprising: acabinet; a drum accommodated in the cabinet; and a dynamic dampenerprovided to dampen oscillations of the cabinet, wherein the dynamicdampener includes: a first mass body provided to move relative to thecabinet to dampen first oscillations transmitted to the cabinet; and asecond mass body provided to move relative to the cabinet to dampensecond oscillation transmitted to the cabinet, wherein the first massbody has a greater mass than the second mass body.
 2. The laundrytreating apparatus according to claim 1, one or more of the first massbody or the second mass body includes: a plurality of overlapping platesand a plurality of connectors coupling together the plurality of plates.3. The laundry treating apparatus according to claim 1, wherein: thefirst mass body has the same lateral width as the second mass body, andthe first mass body has a front and rear width greater than that of thesecond mass body.
 4. The laundry treating apparatus according to claim1, wherein the first oscillations are generated when the drum rotates atfirst range of rotational speeds, and the second oscillations aregenerated when the drum rotates at second range of rotational speedsthat are relatively lower than the first range of rotational speeds. 5.The laundry treating apparatus according to claim 1, further comprisinga buffer pad provided on at least one of a top surface or a bottomsurface of one or more of the first mass body or the second body.
 6. Thelaundry treating apparatus according to claim 1, further comprising abuffer pin passing through at least one of the first mass body or thesecond mass body, wherein upper and lower ends of the buffer pin extendthrough, respectively, top and bottom surfaces of the at least one ofthe first mass body or the second mass body.
 7. The laundry treatingapparatus according to claim 6, further comprising a support plateconnected to the cabinet, wherein: the first mass body and the secondmass body are movably positioned on a top surface of the support plate,the upper end of the buffer pin spaces the top surface of the at leastone of the first mass body or the second mass body from an interiorsurface of the cabinet, and the lower end of the buffer pin spaces thelower surface of the at least one of the first mass body or the secondmass body from a top surface of the support plate.
 8. The laundrytreating apparatus according to claim 1, further comprising: a supportplate connected to the cabinet, the first mass body and the second massbody being movably positioned on a top surface of the support plate; anda coupling bolt that passes through a through hole of at least one ofthe first mass body or the second mass body and is fixed to the supportplate to prevent the at least one of the first mass body or the secondbody from being separated from the support plate.
 9. The laundrytreating apparatus according to claim 8, wherein the through-holeincludes an oblong hole that extends longitudinally in a movingdirection of the at least one of the first mass body or the second massbody.
 10. The laundry treating apparatus according to claim 9, wherein ahead portion of the coupling bolt has an outer diameter greater than alength of a short side of the through-hole.
 11. The laundry treatingapparatus according to claim 1, further comprising: a support plateconnected to the cabinet, the first mass body and the second mass bodybeing movably positioned on a top surface of the support plate; asupport provided between the first mass body and the support plate toguide a sliding movement of the first mass body; and a slider providedbetween the second mass body and the support plate to guide a slidingmovement of the second mass body.
 12. The laundry treating apparatusaccording to claim 11, wherein the support includes: a guide roller; anda roller support body mounted on the support plate to rotatably hold theguide roller, the roller support body including: a seating plate coupledto a top surface of the support plate; and a plurality of guide bossesprotruding from a top surface of the seating plate.
 13. The laundrytreating apparatus according to claim 12, wherein a guide hole having anoblong shape is formed in the first mass body, and one of the pluralityof guide bosses is inserted into the guide hole.
 14. The laundrytreating apparatus according to claim 11, wherein the slider includes:an upper slider mounted on the second mass body; and a lower slidermounted on the support plate, wherein when the second mass body moves onthe support plate, the upper slider frictionally moves on the lowerslider.
 15. The laundry treating apparatus according to claim 14,wherein: a plurality of coupling protrusions protrude from a top surfaceof the upper slider, a plurality of coupling holes are defined in thesecond mass body, and the plurality of coupling protrusions are insertedinto the plurality of coupling holes to couple the upper slider to thesecond mass body.
 16. A laundry treating apparatus comprising: acabinet; a drum accommodated in the cabinet; and a dynamic dampenerprovided to dampen oscillation of the cabinet, wherein the dynamicdampener includes: a first mass body provided to move relative to thecabinet to dampen first oscillations transmitted to the cabinet; and asecond mass body provided to move relative to the cabinet to dampensecond oscillation transmitted to the cabinet, wherein a length of thefirst mass body in a direction of relative motion for the first massbody corresponds to a length of the second mass body in a direction ofrelative motion for the second mass body, and a width of the first massbody in a direction crossing the direction of the relative motion forthe first mass body is greater than a width of the second mass body in adirection crossing the direction of the relative motion for the secondmass body.
 17. The laundry treating apparatus of claim 16, wherein thefirst oscillations are generated when the drum rotates at first range ofrotational speeds, and the second oscillations are generated when thedrum rotates at second range of rotational speeds that are relativelylower than the first range of rotational speeds.
 18. The laundrytreating apparatus of claim 16, further comprising: a support plateconnected to the cabinet, the first mass body and the second mass bodybeing movably positioned on the support plate; and a one or more of aroller or a ball bearing provided between the first mass body and thesupport plate and positioned away from the second mass body.
 19. Thelaundry treating apparatus of claim 18, further comprising: a frictionplate provided between the second mass body and the support plate andpositioned away from the first mass body, the friction plate imparting afriction force during a relative motion of the second mass body.
 20. Thelaundry treating apparatus of claim 18, further comprising: an firstelastic damper that is positioned between a side edge and a bottomsurface of the first mass body and the support plate, and a secondelastic damper that is positioned between a side edge of the second massbody and the support plate.